Add-ins
Where this stands
One published detection covers this technique. Every one is unverified — no rule on Siemphony has been executed against real telemetry.
What the technique is
Adversaries may abuse Microsoft Office add-ins to obtain persistence on a compromised system. Office add-ins can be used to add functionality to Office programs. There are different types of add-ins that can be used by the various Office products; including Word/Excel add-in Libraries (WLL/XLL), VBA add-ins, Office Component Object Model (COM) add-ins, automation add-ins, VBA Editor (VBE), Visual Studio Tools for Office (VSTO) add-ins, and Outlook add-ins. Add-ins can be used to obtain persistence because they can be set to execute code when an Office application starts.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN0137
An adversary writes or drops a malicious Office Add-in (e.g., WLL, XLL, COM) to a trusted directory or modifies registry keys to load malicious add-ins on Office application launch. Upon user opening Word or Excel, the add-in is automatically loaded, triggering execution of the payload, often spawning scripting engines or anomalous child processes.
- AN0138
Malicious Office add-ins loaded via VSTO, COM, or VBA auto-load paths. Upon launch of Word/Excel/Outlook, the add-in executes code without user action. Add-in resides in trusted directory or registered via Office COM/VBE subsystem. Behavior includes unsigned add-in execution, anomalous load context, or add-in spawning interpreter process.
Technique names and descriptions © MITRE ATT&CK®, CC BY 4.0. Not endorsed by MITRE.